He killed Mozart!

Kind of a hilarious take I figured too, even though it flew right over my head as a kid when I saw this in the theater (having never seen AMADEUS). It's amazing when the odd movie casts an actor whose presence actually impacts upon the plot, which must have meant they were either always in mind for the role or that it was rewritten once they were cast. Another example is OCEAN'S 12 in which Julia Roberts's character exists in a world where there is a famous actress who looks like her named Julia Roberts (though a world in which there's no George Clooney, Brad Pitt, etc).

It brings to mind that every film ever made is essentially a sci-fi/fantasy, because they all exist in a parallel universe in which there aren't actors who look exactly like the characters they play in the film. Otherwise you'd routinely have characters approaching Jason Bourne and telling him that he looks amazingly like Matt Damon.